Gas turbine engines are generally known in the art and used in a wide range of applications, such as propulsion engines and auxiliary power unit engines for aircraft. In a typical configuration, a turbine section of the engine includes turbine components such as rows of stator vanes and rotor blades disposed in an alternating sequence along the axial length of a generally annular hot gas flow path. The rotor blades are mounted on the periphery of rotor disks coupled to a main engine shaft. The stator vanes are coupled to inner and outer endwalls and optimally direct hot combustion gases to the rotor blades, thus resulting in rotary driving of the rotor disks to provide an engine output.
The stator vanes and rotor blades typically have arcuate shapes with generally concave pressure sides and generally convex suction sides extending axially in chords between opposite leading and trailing edges. During operation, the aerodynamic contours of the stator vanes and rotor blades, and corresponding flow passages therebetween, are configured in an attempt to maximize energy extraction from the combustion gases. Since higher engine efficiencies may occur at higher temperatures, some turbine components may additionally include internal cooling passages to enable such high temperature operation.
Given these considerations, turbine components may have relatively complex three-dimensional (3D) geometries that may raise difficult fabrication and repair issues. Conventional fabrication techniques include forging, casting, and/or machining. For example, in one conventional casting process, a ceramic core is assembled into a wax tool that will provide the external shape of the component, the core is encased in wax, a ceramic shell is formed around the wax pattern, and the wax is removed to form a ceramic mold. Molten metal is then poured into the mold, cooled and solidified, and then the external shell and internal core are suitably removed to result in the desired turbine component. The cast turbine component may then undergo subsequent manufacturing processes such as machining, electrical discharge machining (EDM) or laser drilling. Such prior art methods are not only expensive and have long lead-times, but may additionally have low yields, particularly in turbine components with complex internal structures such as cooling passages.
Accordingly, it is desirable to provide improved manufacturing methods for turbine components that enable improved cycle times and reduced costs without sacrificing component performance or durability. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.